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Format 800K MFS with 64K ROMs

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I thought this deserving of its own separate post as the previous deals mainly with the flashing LED on the A9M0106 Apple 3.5" Drive.

 

A little history, Larry Pina mentions in his book "Macintosh Repair & Upgrade Secrets" on page 192 that a 128K with an 800K internal drive works just fine, giving you 800K of MFS storage. However, as I've criticized Pina before, he briefly mentions something ground breaking in passing, but gives few details, leaving the reader to infer that there's little else to it. Indeed, I stumbled on the solution accidentally and just assumed everything was working like Pina indicated. Then when I tried to repeat my success, suddenly the thing didn't work. This then is the result of backtracking through my original efforts and what I know know to be true.

 

ONE WORD OF CAUTION before you proceed. This is not yet etched in stone. The following procedures worked on my equipment and due to some fluke of hardware, may not be repeatable on other equipment. No one should assume this is a universal solution until it has been confirmed by others on this list.

 

First something I know to be true of both the Macintosh 128K and 512K. As Pina indicates, both of these Macs will boot from an internal 800K drive as long as it is Apple part number 661-0345 (Sony p/n MFD-51W-03), no other earlier drive mechanism will work (though possibly some later models). These drives will also read and write 800K MFS only disks. The Apple 3.5" Drive (Apple p/n A9M0106) which contains the afore mentioned drive mechanism, will also boot, read and write 800K MFS. However, the original Apple 800K External Drive (Apple p/n M0131) will not work without the HD20 INIT and then only to read and write pre-formatted 800K MFS disks as well as HFS) and you cannot boot from this drive with 64K ROMs.

 

Now for the rub. What Pina does not go into, is how exactly you get 800K MFS disks from which to read/write and boot on a 128K. And perhaps there's a good reason for that. Using System .97/Finder 1.0, S2.0/F4.1, S4.1/F5.5, I was unable to get a 128K or 512K to initialize/format an 800K MFS disk in either the internal or external drive. As JDW pointed out earlier, using the HD20 on the 512K only results in formatting an HFS 800K disk, which is unreadable without the HD20 INIT. So I settled for formatting a 400K MFS Single Sided disk both with the HD20 INIT and in a 400K external drive. Unfortunately, though readable in the 800K drives, any attempts to erase them as 800K MFS resulted in failures or system crashes without the HD20 INIT. The same thing happened with HFS formatted 800K disks (I did not try 400K HFS). So how do you do it?

 

One method that has been posted around the net, though does not specifically say so, requires a Mac Plus or 128K ROMS. Basically you boot up with a stock System 2.0/Finder 4.1 or earlier (the last MFS only System & Finder and pre-HFS aware), the MacPlus does not care about the HD20 INIT or need any other modifications to the basic system. For my purposes I used exclusively a MODIFIED (see below) 2.0/4.1 and everything that follows is based on that unless stated otherwise. Boot up with this system on a Mac Plus or 512Ke, possibly even a 128Ke (128K ROMs in a 128K Mac – not tested) and insert a blank 800K disk. If it is unformatted the Mac will ask you if you want to initialize and about :30 later, you'll have an 800K MFS disk. Even if the disk is formatted, Erase will accomplish the same thing. The resulting disk will work just fine in a stock 128K and 512K using one of the appropriate 800K drives.

 

Now you're asking the same question I was: so what good does that do me if I have 64K ROMs? Since you have to have 128K ROMs or the HD20 INIT to format in an 800K drive and the HD20 INIT will only let you format HFS, you're stuck right? WRONG. You're going to love the solution. The HD20 INIT was released with System 2.1/Finder 5.0 (the FIRST HFS aware System & Finder as far as I know) along with the HD20 Hard Drive. The Mac Plus with 800K drives quickly followed with 3.0/5.1 and that quickly followed by a succession of updates resulting in what is the widely accepted stable system 3.2/5.3 which Pina and others reference for use with the HD20 & 800K drives. The reason the MODIFIED (see below) 2.0/4.1 trick works on the Plus & 512Ke is that the System & Finder don't know about HFS, so I suspect the ROM translates the 800K driver info for it and then the Finder acknowledges 800K capacity, but it still only understands MFS. Once the disk is formatted with the disk capacity information, the Finder no longer needs the ROM to translate and any Finder will happily see the disk as 800K MFS. Now what?

 

Now, put a copy of the HD20 INIT on System 2.0/4.1 (and possibly earlier) MODIFIED with the S3.2/F5.3 Printer Installer (v1.1) AT ImageWriter (v2.3) ONLY (see below). Yup! When the system boots instead of "Hard Disk 20 Startup", it will say "Disassembler Installed". Once loaded you will have an MFS ONLY AWARE environment, but the HD20 INIT evidently tells the Mac all about ANY 800K disk attached to it. That's right, this not only works with the recommended drives but also the original 800K External Drive (M0131) and any 800K drive mechanism (but you will not be able to boot from any but the recommended drives, just like with an HD20 Hard Drive). Just pop a blank 800K disk into any 800K drive and choose Initialize from the dialogue box and you'll soon have a newly formatted 800K MFS disk. Just for the record, I used version 1.1 of the HD20 INIT. As it turns out, I was using my 512K, not my 128K and have been using exclusively early Systems & Finders recently. Somehow I had inadvertently gotten my disks mixed up and accidentally copied the HD20 INIT to the MODIFIED (see below) 2.0/4.1 disk without realizing it and had been using that system with an HD20 Init, which was the last thing I would have ever expected to work as it does. So when I was happily initializing 800K MFS disks with it, I just assumed Pina had been right all along. Only when I retraced my steps did I discover the "Disassembler Installed" startup screen which I had never seen before (well once long ago, but I knew I did not presently have a copy of MacsBug to install – anybody got one?).

 

Now for the dropping of the other shoe: the HD20 INIT will still not load on the 128K Mac (at least with v1.1 & S2.0/F4.1). But all is not lost. Referring back to the numerous misleading, erroneous and poorly detailed tutorials on formatting an 800K MFS disk, this one caught my eye on Google's comp.sys.mac digest. Declan A. Rieb indicates that once you've formatted and 800K MFS disk with 128K ROMS, take the blank 800K MFS formatted disk, write protect it and use it as a master to duplicate more on a 64K ROM system using a copy utility like SUM's Quick Copy (precursor to Norton Utilities). Well I tested it with Copy II 7.0 and was able to make a "Sector Copy (WITHOUT FORMATTING)" in about the same time as initializing using the Mac's initialization package. It made a perfectly usable and bootable MFS 800K blank disk copy from an unformatted disk out of the box (I should also try the Mac 128K Copy Utility). One note here, if the disk copy utility formats the disk, it may not work and you'll see the same crashes as with trying to format with the Mac's initialization package. While this is not the preferred method for initializing new disks on the 128K, it ain't bad! As I said earlier, once the disk is formatted with 800K you can erase it all you want. The disk retains the 800K formatting instructions, in much the same way as my SCSI ZIP 100 drive retains the 4.2 driver after formatting under System 6.0.4 and will boot from System .97/Finder 1.0 up on my Mac Plus, regardless of how many times I erase it with the Finder.

 

I hope this proves as interesting for you as it did for me. Now, before we go spreading the results all over the web, it would be great if members on this forum could check the procedures on their own Macs as well as some additional testing I was unable to quickly do. I do intend to continue in my efforts to combine different Systems and Finders to see if there is a way to initialize an 800K MFS disk using just the Finder, though I suspect the above solution is the bit Pina forgot to include in his book. You'll note earlier I didn't try any system 3.0 combinations, though that's worth a stab. I also want to experiment with other drive combinations as well.

 

Happy MFS-ing!

 

PLEASE NOTE: The stock System 2.1/Finder 4.1 may NOT work as described by JDW below. Please see my subsequent post in which it was discovered the System 2.1/Finder 4.1 I used above had been modified with the 3.2/5/3 Printer Installer (v1.1) AT ImageWriter (v2.3) ONLY . While This procedure absolutely works, stay tuned for the missing piece to the puzzle, so that you can do it too.

Edited by Guest

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"Disassembler Installed" startup screen

Did you mean to say "MacsBug Installed"?

 

MacsBug for 128K and 512K macs are around - I got my copies from the Macintosh 68000 Development System disks (MDS).

 

I even have some old, pre-release, typewritten documentation for it (which comes in handy since the commands are quite different from version 6.*)

 

Ken

Edited by Guest

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All I can say is, wow! My hat's off to you, Mac128. You obviously spent a lot of time performing these detailed experiments (and writing up the results with enviable clarity).

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Kallikak wrote:
Mac 128 wrote:

"Disassembler Installed" startup screen

Did you mean to say "MacsBug Installed"?

 

Actually, I meant "Disassembler Installed". For whatever reason when the HD20 loads under System 2.0/Finder 4.1 that is the onscreen message. Apple shows it as an uncommon error code.

 

Obviously the HD20 INIT is not supposed to work with an MFS only system, but I am at a loss to explain why that message is called, or why it works at all. Looking at the Apple error table, since the HD20 INIT was supposedly unknown to the earlier System, it may have used the same error code as the disassembler and in later System versions the disassembler error code changed to a different number, however odd that seems.

 

I am anxious to try version 1.0 of the HD20 INIT and see if it manifests any differently as well as possibly working on the 128K, but I seem to recall reading that the version change represented just a bug fix. I did test v1.1 of the HD20 INIT on System .97/Finder 1.0 and it did not load. So that really only leaves S1.1/F1.1g. There is of course the possibility of testing different Finders with different system releases. It now occurs to me why using the HD20 INIT in an earlier system/finder didn't happen or occur to others at the time. If this combo will let an MFS system see an 800K disk, will it let it see the HD20 Hard Disk itself? If so, how stable would it be? Would this allow the HD20 Hard Disk to reliably operate as a 20MB MFS formatted hard disk? Would it allow an HD20 attached 800K external disk drive to work as an MFS volume as well? Anyone with a working HD20 HD should check this out for sure! If it does work, you'd be locked into a very early system environment, but heck as far as the stock 512K is concerned, that's just as well.

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SOMETHING INTERESTING/CAUTION

 

When the HD20 INIT is used with System 2.0/Finder 4.1, something very interesting happens. Not only does it allow an MFS system to see an 800K disk and format it MFS, it also allows it to read an HFS formatted disk inserted into the 800K drive.

 

Normally with 64K ROMs under an MFS system, an HFS disk inserted would not be recognized by the system without the HD20 INIT installed and a dialogue box would appear asking if you wanted to initialize the disk. Surprisingly this configuration allows it to read HFS formatted disks. But since it doesn't know from HFS, the disk appears as if it's MFS, no extra pixels in the disk window header, so you can't tell them apart at all. And there's no telling what writing to an HFS formatted disk with an MFS only system would do to the disk. So be aware.

 

The same thing happens using pre-HFS systems with 128K ROMs, but I certainly didn't expect it to happen with the HD20 INIT that seemingly should not even work with a system and finder that aren't aware of it. This really sheds some light on what the HD20 actually tells the system when it loads.

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...put a copy of the HD20 INIT on System 2.0/4.1 (and possibly earlier). Yup! When the system boots instead of "Hard Disk 20 Startup", it will say "Disassembler Installed"... Just pop a blank 800K disk into any 800K drive and choose Initialize from the dialogue box and you'll soon have a newly formatted 800K MFS disk. Just for the record, I used version 1.1 of the HD20 INIT.

I have not been so successful. Today, I tried System 2.0 / Finder 4.1 with the HD20 INIT (ver. 1.1), and I get no special messages at all in the Welcome to Macintosh dialog (no "Disassembler Installed" nor anything else). My external 800k drive LED doesn't flash once either, which it normally does at the same time the HD20 INIT loads during boot. And when I get to the Finder and insert a disk into my 800k drive, I hear the buzzing motor sound, which is indicative of the HD20 INIT not having been loaded. I then put in a formatted 800k disk, and the Mac asks me to initialize it because it can't understand my 800k disk. And when I initialize, only one second later I get an Initialization Failed error dialog. All those shows the HD20 INIT is not loading for me on a 400k System 2.0 / Finder 4.1 floppy inserted into the internal 400k drive of my Mac 512k (with 64k ROMs).

 

Yes, yes, I made 5 different disks with System 2.0 / Finder 4.1 / HD20 INIT 1.1, with the Systems and Finders copied from 5 different working sources. This proves I didn't have a bum copy of the System or Finder. I also know for a fact which versions I am using because you can check the Finder version from the Apple menu in the Finder, and I have a little app called System Version that I double-click to tell me which version of the System I am using. Yes, I am indeed using System 2.0 and Finder 4.1. And yet, even though it is version 1.1 and was placed in the same "System Folder" as the System and Finder, the HD20 INIT won't load.

 

And if you're wondering, no, I didn't have my 800k external floppy drive connected via my HD20 hard disk. I had my 800k floppy drive directly connected to my Mac.

 

But my tests didn't stop there. I tested System 1.1 and Finder 4.1 on a 400k disk, along with the HD20 INIT. The disk boots to the Finder but the INIT doesn't load -- can't see or initialize 800k disks.

 

I then tried System 1.1 and Finder 1.1g with the HD20 INIT. The disk boots but the INIT won't load -- can't see or initialize 800k disks.

 

I then tried System 3.0 and Finder 4.1 with the HD20 INIT. The disk boots and the HD20 INIT loads! But, it doesn't make MFS 800k disks. You see, even though the HD20 INIT loads with System 3.0 and Finder 4.1, and even though it can see my 800k disks when I insert them at the Finder, and even though I can choose Erase Disk and have the disk erase, and even though it shows me "799k free" after I erase the disk, if I then boot into an HFS aware System/Finder, I see the single pixel at the upper left corner of every open window on my 800k disk, which proves my 800k floppy is still HFS. Only MFS disks lack that extra pixel. And keep in mind you won't see the extra pixel when using a non-HFS aware system, like System 3.0 and Finder 4.1.

 

And so, it is clear there is some missing variable here, because I tried different System/Finder combinations and was not able to make an MFS 800k disk. And like I said, based on what Mac128 wrote about his success with System 2.0, I tried 5 times with 5 different floppies using System 2.0 but without success. But for whatever reason, the HD20 INIT loads for me with System 3.0! Nevertheless, it doesn't create MFS 800k disks.

 

Thoughts would be appreciated. (And of course, it would certainly be nice if a few other of you Mac 512k owners out there could also kindly test this along side Mac128 and myself. No doubt more than two of us on this planet who read this forum have a Mac 512k with 64k ROMs.)

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HOLD THE PHONE EVERYBODY.

 

Once again a lesson learned about using old files without thoroughly vetting them. JDW, I too have all of the resources that you are using. In particular, I have the little application called SysVersion which tells me the current system version. When I run it, it reports "System 2.0 08-Apr-85". About the Finder under the Apple Menu also reports 4.1.

 

HOWEVER, upon JDWs failures with my discovery, I chose Get Info from the file menu for both the System and the Finder. The Finder reports a creation date of May 2, 1984 which is far too early for Finder 4.1 which was released almost a year later. This date corresponds with Finder 1.1g. The System reports a creation date of June 2, 1986! Over a year later than System 2.0 was created. However, it does correspond with the release of System 3.2.

 

I am at a loss to explain why both the Finder and SysVersion report completely different creation dates from the respective versions. Obviously the system and Finder both have been modified. Hopefully you won't hold it against me given my efforts to confirm the software I was using.

 

Now, I have one idea what may have happened here. I believe this disk was the result of an original System 1.1/Finder 1.1g being upgraded to System 2.0/Finder 4.1 to add AppleTalk to the system and then further upgraded with the System 3.2/Finder 5.2 "System Installation v1.0" disk and a custom install of AppleTalk, External Drive, or Printer Installation. That at least matches all the reported creation dates. Not knowing how those old installers worked I would have thought any upgrades would have just swapped out the System and Finder files completely. Evidently, sometimes they were, other times they were modified. Point is, this was not a clean copy of 2.0/4.1, but it's also not something weird either, since it was created using Apple's install disks. FYI, AppleTalk was installed as part of the AT printer installation package, not an AT workstation client install.

 

At this point, I would say System 3.2/Finder 4.1 is the ticket to make my tutorial work. Having said that, the installation of AppleTalk is the likely missing ingredient here. JDW indicated that Finder 4.1 still didn't work with System 3.0 to format MFS, but perhaps it will work with System 3.2 without the installation of AppleTalk, though I somehow doubt it ...

 

At this point, until I figure out how this altered system came to be, please TEST AT YOUR OWN RISK. I realize this kind of thing can be time consuming so I apologize to anyone who has been trying to make my seemingly "straight forward" method work. I've been there and it can most frustrating.

 

Nevertheless, what I say does in fact work. At this point it is a matter of retracing the steps used to create this obviously unique system combination. As JDW pointed out, System 3.0 would only create HFS 800K disks using Finder 4.1 and verified them using an HFS startup disk. I certainly did no less with my 800K MFS formatted disks in checking them under an HFS startup disk. The disk windows clearly show the extra pixels on the HFS Startup Disk and no extra pixels on the 800K MFS formatted disk, or other known MFS 400K disks, though known HFS disk show up with the extra pixels. (one side not here, the HD20 INIT should work with System 3.0 as it was originally release with System 2.1 and yes I would expect HFS from System 2.1 forward using the HD20 INIT)

 

Clearly what has happened is that some resource has been added to the MFS only System 2.0/Finder 4.1 that enables it to understand HFS & 800K disks without giving it the ability to write HFS. My understanding about AppleTalk in trying to understand why AppleShare clients won't work on a 128K goes back to the extra memory required to load the HFS instructions (Inside Macintosh actually explains why AppleShare on a 128K is an impossibility). AppleShare by definition requires HFS in order to read and write HFS AppleShare Server volumes. However, AppleTalk was originally available on the 128K for printer sharing. Indeed Infosphere's MacServe and Suns TOPS were making good use of disk & file sharing networks via AppleTalk long before Apple made the move to HFS and using their own drivers, not Apple's. So the operating theory here is that the Addition of AppleTalk alone to drive a printer network on these MFS systems imparted some critical information that enables these older systems to make use of the HD20 INIT without actually adding HFS.

 

I will get to the bottom of this eventually,in the meantime, anyone else who wants to help me deconstruct this mess, is greatly appreciated.

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REPRODUCING MY STEPS: THE SOLUTION (hopefully)

 

I'm happy to report that I reproduced the steps that led to the MODIFIED 2.0/4.1 System. While there may be other solutions, this is mine:

 

I did indeed start with a clean copy of System 1.1/Finder 1.1g (I don't know if this is necessary, but it's what I did).

 

Then I used System 2.0/Finder 4.1 Update disk and the included installer to update my 1.1/1.1g. It may well be possible to simply start with this system and continue from this point. However, I have not tested it and am going to leave it to someone else for the time being. It is interesting to note that while this system has a Chose Printer DA that features buttons to turn AppleTalk on and off the option is grayed out following the update.

 

This next step I think is the KEY: I used the Printer Installation disk (v1.1) which came with the System 3.2/Finder 5.3 update (also known as System Installation v1.0). Using the installer I performed a custom install of just the AppleTalk Image Writer (v2.3). You must use the installer as the System must be modified to use AppleTalk. Dragging an AT Image Writer INIT to the System Folder won't do it.

 

Lastly I copied v1.1 of the HD20 INIT to the system folder and that's it.

 

I made two separate disks from the ground up and both started up as described in my initial post and were able to initialize MFS 800K disks as before.

 

Now that I know the exact procedure and can reproduce it, I would love to hear others are able to do the same. The great thing about this, is that it truly is not a hack. It's simply updating an older system with a newer version of a printer driver. Somehow installing the AT Image Writer alone results in a partial update to System 3.2 without changing the version number resource, but it puts the version number 3.2 in the Comments box. The SysVersion application still shows 2.0. Apple probably never intended for this to happen and I'm not sure I would run a system like this, but it seems to make stable 800K MFS disks.

 

One important note in trying to test formatting between HFS, MFS, 400K & 800K environments ... and I have read this before ... once you format a disk as 800K, never go back to 400K. The same seems to be true for HFS & MFS. Don't try to go back and forth with the same disk. Once you format a disk as 800K MFS, leave it that way, don't try to reformat it to 400K or even HFS. And definitely don't format an 800K HFS disk and try to reformat to anything else. As a result of sorting all this out, I've got some pretty messed up disks (some even ended up with 1440K somehow)!

 

My fingers are crossed that this is the final solution. I look forward to other's findings ...

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Kallikak wrote:
Mac 128 wrote:

"Disassembler Installed" startup screen

Did you mean to say "MacsBug Installed"?

 

Actually, I meant "Disassembler Installed". For whatever reason when the HD20 loads under System 2.0/Finder 4.1 that is the onscreen message. Apple shows it as an uncommon error code.

 

Interesting. You might want to have a look inside the DSAT resource of that System File - be interesting to see if the more usual MacsBug Installed message is there, or if it has been overwritten by the Disassembler Installed message.

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Mac128 kindly emailed me a couple disk images. I found that the first image he sent to me ("2041HD20 copy.img") boots my Mac 512k just fine. I put version 1.1 of the HD20 INIT on it and rebooted. It now shows "Disassembler Installer" in the Welcome to Macintosh box and it does indeed format 800k disks as MFS (in my external 800k floppy drive)! Yeah! So clearly, something is unique about this System 2.0 file!

 

Since Mac128 mentions a "Update Disk" I would like to add that one of the five System 2.0's I tested yesterday was taken from a MAY 1985 System Update disk that has System 2.0 and Finder 4.1 on it. But clearly this "already updated" disk was not updated in quite the same way as Mac128's disk was! Because like I said in my post yesterday, I tried System 2.0 and Finder 4.1 from five different sources, and the HD20 INIT would not load at all (hence, it could not see or erase 800k disks).

 

So after successfully testing Mac128's "magic" disk today, I then decided to test my own copy System 3.2 and Finder 4.1 and the HD20 INIT (as Mac128 asked me to do in his post yesterday), but this acts just like System 3.0 & Finder 4.1, which I reported in my previous post (it can see and format 800k disks, but only as HFS). I then pulled System 3.3 off an Apple WorkStation Installer disk (with Appleshare 1.1) and combined that with Finder 4.1 and the HD20 INIT. Nope. Still acts like my System 3.0 and Finder 4.1 test disk did.

 

So it is quite clear that formatting 800k disks as MFS requires a very special copy of System 2.0 to work! (Or another, older System that has whatever "magic" resources are necessary to make 800k MFS disks in conjunction with the HD20 INIT).

 

And so, I decided it would be prudent to compare my System 2.0 file (which cannot make MFS 800k disks) with the "magic" System 2.0 file Mac128 sent me. I compared the files using ResEdit. Here are the general differences I spotted (resources I don't mention below "look the same" to me):

 

JDW's System 2.0 File (i.e., "Normal" System 2.0)

  • no bmaps resource
    no ctabs resource
    ALRTs: ID -15775
    DITLs: -15936=30, -15775=52, -15776=174
    DLOGs: -15936=29, -15776=21
    DRVRs: fewer in number
    no LDEF resource
    no NBPC resource
    no ncts resource
    no nrct resource
    PACKs: fewer in number
    has PAPA resource
    no PTCH resource
    no tlst resource
    no WIND resource

Mac128's System 2.0 File (i.e., "Magic" System 2.0)

  • has bmaps resource
    has ctabs resource
    ALRTs: ID -15808
    DITLs: -15808=242, -15807=52, -15775=38, -15776=182
    DLOGs: -15808=28, -15807=34, -15776=28, -15775=21
    DRVRs: more in number
    has LDEF resource
    has NBPC resource
    has ncts resource
    has nrct resource
    PACKs: more in number
    no PAPA resource
    has PTCH resource
    has tlst resource
    has WIND resource

Before I do any further testing, I would appreciate hearing everyone's thoughts on this.

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AT LAST! THE FINAL WORD

 

Whatever further testing reveals, my previous posting DOES IN FACT WORK on other Macs and is reproducible through easy documented steps:

 

1. Start with Clean 1.1/1.1g System (possibly skip this step)

2. Use 2.0/4.1 Updater (possibly start with clean 2.0/4.1 System & skip step 1)

3. Use 3.2/5/3 Printer Installer (v1.1) to add AT ImageWriter (v2.3) ONLY

4. Add HD20 INIT

 

I can tell you for certain that the HD20 1.0 INIT DOES WORK in addition to the 1.1 INIT.

 

I would now like to know if you can skip the system 1.1 step and just start with a clean copy of 2.0/4.1. Also, there was a previous version of the AT ImageWrier installer (v1.0) that appeared on the System 3.1/5.2 Installer disks. I would be curious to know if this works as well, though I understand 3.1/5/2 contains a serious bug which might be conveyed in the system resources it updates. Likewise, I would like to know whether the AT Imagewriter installer will work on System 1.1 w/HD20 INIT, though I don't suspect it will since 1.1 pre-dates Apple's introduction of AppleTalk applications. But you never know.

 

As a separate experiment, anyone with an HD20 willing to reformat under this system, it would be fun to learn if an HD20 can be run under this system as well as be formatted MFS ONLY. Perhaps it would run better! Seriously, I have often wondered about MFS & HFS. From its release the Macintosh was criticized for not having a hard drive. So, when did Apple actually start thinking about moving to HFS vs. when they started thinking about adding a hard drive to the Mac. If the HD came first, it may have been planned as an MFS drive from day one.

 

Finally I want to give a HUGE nod to Eric Rasmussen and his Apple Macintosh before System 7 site, where you will find all of the necessary files (except System 1.1) to make the modified System 2.0. I consulted with Eric for several months a few years ago and I hold his information as the most comprehensive and accurate posted anywhere on the net. All of which was thoroughly documented through not only reconciling available resources, but from actually assembling complete systems and software packages. It is an invaluable resource for those of us who are trying to piece together the past in an effort to keep our old Macs alive and productive.

 

For those of you who have visited my dedicated 128K site, you'll know the reason why this system and 800K MFS is important to me is because it is vital to maintaining and transferring files to my 128K. Since the 128K can't use HFS disks or AppleTalk or TCP/IP, with an external 800K MFS drive I can easily transfer virtually any file from my OS X Intel MacBook directly to it and keep archives of files that way. It also allows me to keep large documents, applications, fonts and systems all on the same disk. For a 128K user, 800K MFS disks are an invaluable tool. It's too bad Apple did not try to assist the 128K user in this regard, but just as I discovered swapping disks yesterday it probably would have resulted in twice as many nightmares as Apple already had upon switching to HFS. I also have a sneaking suspicion that Apple or Jobs, or both, wanted to distance themselves from the 128K "mistake" (that most literature indicates blame for which was placed squarely on Jobs and his dictates) as quickly as possible.

 

Thanks to JDW and for everyone who participated in the resolution of this issue.

Edited by Guest

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...anyone with an HD20 willing to reformat under this system, it would be fun to learn if an HD20 can be run under this system as well as be formatted MFS ONLY. Perhaps it would run better!

I spoke a little about this in the 3rd & 4th paragraphs of this post. So you can see the logic behind the point about "paritioning" the HD20. However, despite having read that Nested Volume Manager article, I am not sure how to do the partitioning myself. But if someone could enlighten me on it, then I can try to reformat/repartition my HD20 while at the same time try an MFS partition along side some HFS partitions. But to make the entire disk MFS would be rather nasty (e.g., in Open/Save Dialogs) in light of MFS being a flat file system, especially if you have a huge number of files on an HD20 like I do!

 

Kudos to Mac128 for solving the 800k MFS issue!

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Well here's a quick question, will this system see your HD20 (since we know it reads HFS files) and if so, does it also see your 800K drive daisy-chained through the HD20? Reading it should cause no problems, but I sure wouldn't write anything to it! If so, that answers part of my question without trying to reformat your drive. If not, then it likely won't be able to reformat it either. It's more of an experiment than practical application. Though if you use the HD20 mainly for applications and disk images, a flat file system wouldn't be so bad.

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Mac128, if I connect my 800k drive to my HD20 and the HD20 to the Mac and then power on the HD20 for 30 seconds and finally switch on the Mac, I can boot off your "magic" System 2.0 floppy in the internal 400k drive until the Welcome to Macintosh box appears. At that point, the "Disassembler Installed" message appears inside the Welcome to Macintosh box and my 800k drive's LED flashes once (showing the HD20 INIT has loaded successfully). The HD20 then begins to audibly access as if it was going to boot, which is a normal part of the HD20 INIT's switching control of the boot sequence from the 400k floppy to the HD20. Unfortunately, the Welcome to Macintosh box starts flickering rapidly at this point and stays that way indefinitely (i.e., crash) and the HD20 stops accessing/booting.

 

I don't think this has anything to do with the fact I have System 4.2 and Finder 6.0 on my HD20. I think it simply is evidence that System 2.0 and Finder 4.1 are too old for the HD20's controller to handle the HD20-INIT's boot changeover process.

 

To verify, I tried my own System 2.0 and Finder 4.1 disk (the one that shows "Hard Disk 20 Startup" in the Welcome to Macintosh dialog and cannot make 800k MFS disks). It too freezes at the same place. So this lends evidence to the fact that System 2.0 is perhaps too old for the HD20's liking.

 

Now, if I switch off the HD20 but leave my 800k drive connected to the HD20, and the HD20 still connected to my Mac; and if I then boot once again from Mac128's magic System 2.0 floppy, I get the Disassembler Installed message in the Welcome to Macintosh box but the floppy boots to the Finder. And at the Finder I found that I was able to format 800k floppies as MFS. So while my HD20 would not boot, the fact that I could still use my 800k drive via the switched-off HD20 shows something, I guess.

 

Anyway, it's clear that more than just the HD20 INIT is required to boot the HD20 hard drive on a Mac 512k with 64k ROMs -- it requires a modern enough System (and possibly Finder).

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NEW EXPERIEMNT

 

JDW, I went back and read your testing methods when I first proposed the "magic" system. (I love that name BTW).

 

After reading your latest with the HD20, I started thinking about why it was necessary to install an AT printer driver from system 3.2.

 

Here's what I came up with, the one thing we overlooked.

 

I took a peek inside the HD20 INIT with Resedit and discovered that it was basically a resource called PTCH and contained 3 files. Basically the ROM "patch". Of the three files the largest was "TFS" which I took to be "everything a 64K ROM needed to know to read and write HFS". Then significantly smaller was ".Sony" which is the disk driver already in every ROM, presumably updated to include 800K drives and the HD20 hard disk. Finally at a mere 290 bytes, something called a "Dispatch Kernel" about which I could not speculate. So I deleted "TFS" and the "Dispatch Kernel". Call me impulsive, but ...

 

Next I replaced this modified HD20 INIT with the clean HD20 INIT in our "magic system" 2.0/4.1 and guess what, it booted up (with no Welcome screen message at all)! But it would not recognize HFS disks, only the 800K drives. That really got me thinking about version numbers. Since the Finder went up to 5.0 in the original HFS HD20 INIT system and we think 4.1 Finder is the reason the 800K disks are formatted MFS instead of HFS in the magic system, I noticed that the first official HFS system was 3.0 when the Mac Plus was released. The HD20 was released with system 2.1. So I put a clean System 2.1 and Finder 4.1 on a disk with the modified HD20 INIT and it worked fine, just like the "magic system".

 

http://FYI, In order to format 800K MFS disks, you must used the MODIFIED HD20 INIT, otherwise it acts just as the regular HFS System. However, even though it reads HFS this way, it does not seem to write it. Folders written to a known HFS disk under this system do not show up correctly under an HFS system.

 

Now I need others to confirm this before I get too excited.

 

Here's what I think though. I think the reason JDW's HD20 doesn't start up with the magic disk is because system 2.0 as he says doesn't know what to do with it. I'd like to see if 2.1 understands it. In your case, you should take the original HD20 startup disk with System 2.1/Finder 5.0 and replace the 5.0 finder with clean 4.1 Finder and see if your HD20 will boot from that. If not, it's a fair bet what the HD20 needs is in the 5.0+ Finder. At least that would solve that question. Now, I agree with you that the system folder on your HD20 does not directly cause the crash you experience ... but indirectly, it just being there might. Keep in mind the HD20 INIT is designed to not only make 64K ROMs HFS, 800K & HD20 aware, but also to look for a system on the HD20 drive and hand off to it and eject the HD20 Startup disk. Most likely some of that is handled by the System itself. If your HD20 did not have a system folder, I wonder if the magic system would have mounted it normally. Alternately, since 2.0 is an MFS system, I wonder if it could actually even see your system inside its System Folder. You might try using magic 2.0/4.1 with the System and Finder loose in drive and see if the crash is the same.

 

If 2.1/4.1 works then try the bare HD20 and see what happens. Maybe even a modified bare HD20 with the .Sony driver and the "Dispatch Kernel", which may be the bit that hands off startup to the hard drive.

 

Unless I find a problem using the modified HD20 INIT, it makes the most sense to use, as it will save you about 24K over the current HD20 INIT. Also, it prevents the 64K ROM from reading HFS disks, possibly causing data corruption.

 

What it does tell me though, is something was added to System 2.1 that tells it to look for the HD20 INIT, that's why it won't work with a clean System 2.0, the System has to know to look for a patch as well as which patch. In this case it must be told to look for "Hard Disk 20", which by the way cannot be re-named like the System & Finder. I also think whatever was added to 2.1 is not the same as what I suspect is the complete HFS overhaul represented by System 3.0. in other words, possibly a quick fix to get the HD20 out the door. (BTW, until I read some marketing info, I did not realize the HD20 had been announced in April '85 but did not ship until September! If what I suspect is true, no wonder they slapped a patch on it and as I've read and did not make much fanfare about HFS when they released it – 'cause it wasn't ready for general release!) The only thing I can think of for why the System 3.2 AT ImageWriter install trick works is that it needs certain resources it also shares with the HD20.

 

What I did not mention here is that the .Sony driver ONLY modified version of the HD20 still will not load on the 128K, which puzzles me since the driver info alone should not add significantly to the System heap enough to keep it from loading into available RAM. That tells me that whatever was added to System 2.1 also specifically instructed the HD20 NOT to load when only 128K RAM was present. This gives me hope for finding and eliminating that code to at least Make the 128K compatible with 800K drives.

 

To summarize: Possible new way to Format 800K MFS disks with 64K ROMS/

Clean System 2.1

Clean Finder 4.1

MODIFIED HD20 INIT ("TFS" resource removed with ResEdit)

No magic.

Edited by Guest

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FYI System comparison:

 

JDW's System 2.0 File (i.e., "Normal" System 2.0)

no bmaps resource

no ctabs resource

ALRTs: ID -15775

DITLs: -15936=30, -15775=52, -15776=174

DLOGs: -15936=29, -15776=21

DRVRs: fewer in number

no LDEF resource

no NBPC resource

no ncts resource

no nrct resource

PACKs: fewer in number

has PAPA resource

no PTCH resource

no tlst resource

no WIND resource

 

Mac128's System 2.0 File (i.e., "Magic" System 2.0)

has bmaps resource

has ctabs resource

ALRTs: ID -15808

DITLs: -15808=242, -15807=52, -15775=38, -15776=182

DLOGs: -15808=28, -15807=34, -15776=28, -15775=21

DRVRs: more in number

has LDEF resource

has NBPC resource

has ncts resource

has nrct resource

PACKs: more in number

no PAPA resource

has PTCH resource

has tlst resource

has WIND resource

 

Mac128's System 2.1 File (i.e., "Normal" System 2.1)

no bmaps resource

no ctabs resource

ALRTs: ID -15775

DITLs: -15936=30, -15775=52, -15776=174

DLOGs: -15936=29, -15776=21

DRVRs: fewer in number

no LDEF resource

no NBPC resource

no ncts resource

no nrct resource

PACKs: fewer in number

has PAPA resource

no PTCH resource

no tlst resource

no WIND resource

 

JDW, from your comparison, it would seem that there is no difference between a clean system 2.1 and 2.0. Whereas, 2.1 contains none of the elements the "magic" 2.0 contains as installed by the printer installer. Yet 2.1 will LOAD a clean HD20 INIT with Finder 4.1 whereas 2.0 won't. Odd. Clearly the necessary code is not in any of the resources compared with the "magic" system, at least in 2.1. But at least that tells me where not to look!

 

In checking my clean 2.0 to 2.1, I find only two differences in the PACKs: ID 2 is larger by 48, but ID 3 almost doubles in size from 3378 to 6552. The only other differences are minor cosmetic additions to DITLs, etc. Unless I missed something, that's the HD20 INIT aware code. Which means the HD20 INIT itself contains everything else.

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Mac128, it looks like you need to email me a clean copy of the S2.1F5.0 disk image.

 

The only place I could find a copy was at this Gamba link (only available for download via Archive.org). That image boots my Mac512 just fine, and it loads its own copy of the HD20 init. It even has HD20 diag apps on it. I then formatted an 800k disk with it and found it to be HFS (of course). I then swapped out F5.0 for Finder version 4.1 and rebooted. I reformatted my 800k disk. This time the single pixel was not present in the upper left of the Window, but when I rebooted with a more modern System disk, the pixel was there. That test shows that even F4.1 wouldn't work the "magic" necessary with System 2.1 to format my 800k disk MFS.

 

But the real problem began when I put Finder 5.0 back on the disk and tried to boot my HD20 with it. With this disk, my HD20 seems like its going to boot, but after 10 seconds of accessing, the Welcome to Macintosh box starts flashing (i.e., crash). So perhaps something is wrong with this System 2.1 disk, hence my need for your fresh copy.

 

Once I have your fresh copy, I will give my testing a go again.

 

Thanks.

 

P.S. Are you certain your copy of this System is version 2.1? Or is it really version 2.0.1? Regardless, I used SysVersion on the Gamba disk and it showed version 2.1.

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Hi, sorry, I didn't make myself clear ... With 2.1/4.1. in order to format MFS 800K disks, you MUST use Resedit to delete all but the ".Sony" driver and "Dispatch Kernel" resource on the HD20 INIT. (I believe the HD20 INIT "TFS" resource has all of the HFS information).

 

As for your experiment with the HD20, I did want you to use the 2.1/4.1 configuration to see if that worked with your HD20 hard disk unaltered. If that worked then it meant that the Finder was irrelevant to starting up with your HD20, then you could experiment with the modified HD20 INIT.

 

I am quite surprised that 2.1/5.0 did not work with your HD20 since it is absolutely supposed to. There were two different drivers 1.0 & 1.1 and it's possible that your drive somehow needs the 1.1 driver and possibly System 3.2/5.3 with which it was released (or at least more resources than 2.1/5.0 has) if that is a factor in how your HD20 was formatted.

 

As for System 2.0.1, I've never heard of such a thing. AFAIK, 2.0 went directly to 2.1.

 

So maybe that Gamba file is somehow modified ....

 

This now makes me curious about using the modified HD20 INIT with System 3.x/Finder 5.x configurations. I'll look at the differences between Finder 4.1 and 5.0 as well. Also, since System 2.0 & 2.1 are minimally different, I'll look at 2.1 vs. 3.0 as well to see what happens with 2.1 & 5.x finders with the modified HD20 INIT ...

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Mac128,

 

I appreciate your emailing me a disk image. The "mfs400k" image you sent me last night had problems again -- I couldn't get DD+ or DiskCopy4.2 to mount it UNTIL I changed the TYPE and CREATOR to what DD+ wanted to see (DD+ formatted image) and then it worked! So I make a 400k floppy with it, switch on my HD20, waited 30 seconds, switched on my Mac512, then inserted the disk made from your image. It got to the Welcome to Macintosh box and then my HD20 started accessing and the disk was ejected. But a second later the Welcome to Macintosh box started flickering (i.e., computer crashed), just as I reported in my last post.

 

Now although I would normally suspect the disk as being bad, the fact is that if I switch off my HD20, I can boot from your disk! And yes, the HD20 INIT on that disk loads.

 

I then proceeded to swap out Finder 5.0 with Finder 4.1. Tried making the 800k MFS disk, but it would only create HFS. So it's clear that I need to do the ResEdit hack on it to enable the MFS formatting for 800k disks. I was brain-dead tired after work this evening, so I didn't feel up to ResEditing today. Perhaps I can do that tomorrow and report back here.

 

But suffice it to say, despite the fact that this System and Finder should theoretically boot my HD20, my findings are that it doesn't work. Like I said, the Welcome to Macintosh box flickers/freezes after the disk is ejected at boot time.

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The only thing I can think for a clean S2.1/F5.0 HD20 v1.0 disk not working on your setup is that whatever system you have installed on your HD20 was formatted and setup with v1.1 tools and S3.2/F5.3 which is somehow incompatible with the older version, especially if you are using a more current system on your HD20 than 3.2/5.3.

 

As I have speculated, System 2.1 may be a patched MFS system that relies solely on the HD20 INIT to patch the system. I'd love to see a Hard Disk 20 manual to see how Apple implemented this for the user. Under that assumption System 3.0, then is a fully HFS aware system that by 3.2 (in a short 5 month span BTW) probably works somewhat differently. I need to compare all of these systems to confirm my theory though.

 

Curious to see what happens with the ResEdit HD20 INIT. At best, I can only hope it will mount the HD20 and allow you to see it on the desktop, but I would not expect the .Sony driver would hand off the system to it. Chances are, without the "TFS" resource, your Mac won't recognize the HFS format on the disk and ask you to initialize, in which case that would tell us, it sees the disk. Try three different hacks:

 

1. "TFS" & .Sony resources ONLY (may allow reading HFS without system handoff)

2. "Dispatch Kernel" & .Sony ONLY (who knows?)

3. .Sony only (should be MFS read only)

 

Something I am also curious about ... when you loaded System 2.1/Finder 4.1 with the normal HD20 INIT and then inserted a known HFS disk, did the extra pixel show up? I'm wondering if that's a feature of the Finder or the System.

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when you loaded System 2.1/Finder 4.1 with the normal HD20 INIT and then inserted a known HFS disk, did the extra pixel show up?

No. The HFS "single pixel" does not show up when I use Finder 4.1 in conjunction with your System 2.1 (or System 2.0). So when I said, in my posts above, that I checked my formatted 800k disks for that pixel, I was implying that I had booted with a more modern system disk that will show that HFS pixel.

 

As to the ResEdit hacks, I will try the variations you suggest when I find the time over the next few days (hopefully today, if I can) and report back here.

 

And yes, my HD20 does have a System and Finder much more modern than the S2.1F4.1 disk you gave me. I am using Finder 6.0 and I think System 4.1 (I'll need to boot my Mac to confirm the System version). But again, this is more modern than the boot disk I was using. Nevertheless, I have always used two different 400k HD20 INIT boot disks without problem to boot from my HD20. One of those floppies has Finder 6.0 and System 4.1, while the other floppy has Finder 5.5 and System 4.1. So this shows that the boot floppy will still hand over control to the HD20 even if the boot floppies Finder is a bit older than the Finder on the HD20. As to the System being older, I will have to test this further and see what happens.

 

Thanks.

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Okay, Mac128, here's my detailed test report using your Magic System 2.1 / Finder 4.1 disk and a patched HD20 INIT. Note that I put System 3.0 and Finder 5.1 on my HD20 to make the HD20 boot with your Magic floppy.

 

(1) Deleted "Dispatch Kernel" but left TFS & .Sony in the HD20 INIT via ResEdit. No "Disassembler installed" message inside the Welcome to Macintosh box, but I see the LED flash and disk motor access on my external 800k drive during boot. I can format 800k disks MFS! Yeah! But the HD20 won't boot with this disk. Instead the disk boots to the Finder, at which time the computer locks up hard, and the arrow cursor cannot be moved.

 

(2) Deleted "TFS" but left Dispatch Kernel & .Sony in the HD20 INIT via ResEdit. No "Disassembler installed" message inside the Welcome to Macintosh box, but I see the LED flash and disk motor access on my external 800k drive during boot. I can format 800k disks MFS! But the HD20 won't boot with this disk. Instead the disk boots to the Finder, at which time the computer asks me if I want to initialize the HD20 or Eject it. No crashes/lockups in this case, but of course, the HD20 won't boot nor is recognized at the Finder (most likely because its HFS formatted).

 

(3) Deleted "Dispatch Kernel" & "TFS" but left .Sony in the HD20 INIT via ResEdit. No "Disassembler installed" message inside the Welcome to Macintosh box, but I see the LED flash and disk motor access on my external 800k drive during boot. I can format 800k disks MFS! But the HD20 won't boot with this disk. Instead the disk boots to the Finder, at which time the computer locks up hard, and the arrow cursor cannot be moved.

 

And there you have it. So while it didn't give us a means of formatting the HD20 as MFS, it was an interesting set of tests. And originally, my HD20 wouldn't boot at all (the Welcome to Macintosh box would flicker and the computer would lock at that point). But before, I had System 4.1 and Finder 6.0 on the HD20. When I downgraded the HD20 to System 3.0 and Finder 4.1, I could make it boot using your Magic disk, so long as I had the unaltered HD20 INIT installed on the floppy.

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Okay, Mac128, here's my detailed test report using your Magic System 2.1 / Finder 4.1 disk and a patched HD20 INIT.

 

OK, keep in mind that 2.1/4.1 is not "magic" it's just 2.1/4.1 unmodified. I chose 2.1 because it is only about 3K bytes different than 2.0 (yet HFS "aware"), whereas 3.0 is significantly different (almost double the size, fonts notwithstanding). The modified HD20 INIT is the only "magic" element this time.

 

Interesting results and thank you. Your second test I do find encouraging. Obviously you don't want to initialize your HD20, but for someone with an HD20 that has nothing on it, I would be most interested to learn the results of clicking "initialize" instead of "eject". Perhaps my HD20 will magically begin working again one day!

 

You did try booting with an unaltered HD20 as well correct? I am somewhat surprised that a clean 2.1 & HD20 INIT did not at least "see" the HFS formatted drive as it does with an 800K HFS disk on my Mac, but perhaps the fact you had a system on your HD20 at all prevented the drive from simply mounting and instead kept locking up as it tried to hand-off the system and the hand-off may require the 5.0 Finder. I would certainly use the exact same system and Finder on your HD20 as the boot disk in any event for these tests. Verifying the clean system 2.1/5.0 HD20 v1.0 INIT compatibility with your current 4.1/6.0 system would be helpful too.

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I would be most interested to learn the results of clicking "initialize" instead of "eject". Perhaps my HD20 will magically begin working again one day!

Clicking "initialize" in order to see if the HD20 is then formatted MFS... Yes, that would be an interesting test. But as I wrote in this post, it would be most practical to first partition the HD20 and then format one partition MFS. Of course, to do that, a programmer among us would need to compile the Nested Volume Manager code here. And if you read through that Nested Volume Manager article, you can see they talk about MFS formatting too. So that article itself lends evidence to the fact people have formatted their HD20's MFS. It just seems that you wouldn't want to format the entire drive as MFS, for reason I mentioned in my other post.

 

You did try booting with an unaltered HD20 as well correct?

My HD20 boots just fine off an unaltered boot floppy that has System 2.1 and Finder 4.1 or higher (I "altered" your original floppy to put Finder 4.1 on it). More specifically, if I used an unaltered HD20 INIT on your System 2.1 disk and with Finder 4.1 on it, it properly hands control over to the HD20 during boot, the floppy ejects, and the HD20 boots and runs just fine (so long as I have System 3.0 and Finder 5.1 on the HD20). But in my 3 test cases above, you can see that I had modified the HD20 INIT on the boot floppy. That's why, in all 3 of those cases, the HD20 did not boot. In other words, if you delete any resource in the HD20 INIT, the HD20 will not boot. So instead, in my 3 test cases above, the boot floppy did not eject -- it continued booting to the Finder. It was at that point that the system either crashed or gave me an "Initialize" dialog for the HD20.

 

Finally, keep in mind that if I put System 4.1 and Finder 6.0 on my HD20, even with a virgin HD20 INIT on your System 2.1 / Finder 4.1 floppy, the HD20 will not boot and instead the Welcome to Macintosh box will flicker and the computer will lock up at that point.

 

I am somewhat surprised that a clean 2.1 & HD20 INIT did not at least "see" the HFS formatted drive as it does with an 800K HFS disk on my Mac

Like I said, per your requests in posts earlier in this thread, I had to alter the System 2.1 disk you gave me. The 2 changes I made were: (1) put the HD20 INIT on it (and all my "test variations" of the HD20 INIT, one at a time) and (2) put Finder 4.1 on it. Once you put Finder 4.1 on your disk, it becomes "magic." Meaning, with Finder 4.1 on it, I can then format 800k disks as MFS. I could not do that simply by adding the HD20 INIT alone to your virgin disk. The reason is because the Finder version you have on your disk was too new. But after downgrading your Finder to version 4.1, it formats 800k disks as MFS.

 

I also found that sometimes I could mount an HFS formatted 800k floppy (with System 2.1 / Finder 4.1 / virgin HD20 INIT), but the HFS floppy's contents would not show up in the Finder (the window would be blank) -- but it didn't ask me to initialize the disk in such a case. Perhaps this unusual anomaly occurs because System 2.1 is HFS aware whereas Finder 4.1 is not.

 

I would certainly use the exact same system and Finder on your HD20 as the boot disk in any event for these tests. Verifying the clean system 2.1/5.0 HD20 v1.0 INIT compatibility with your current 4.1/6.0 system would be helpful too.

I did confirm that your virgin System 2.1 / Finder 5.0 disk would not boot my HD20 if my HD20 had System 4.1 and Finder 6.0 on it. However, I did not try to test my HD20 using your System 2.1 and Finder 5.0, nor did I try using your System 2.1 and Finder 4.1. But like I stated above, Finder 5.0 prevents me from making 800k MFS disks, so there's little value in me testing that case. However, testing System 2.1 and Finder 4.1 on my HD20, and then trying the S2.1F4.1 boot floppy with a virgin HD20 INIT may be an interesting test. If it works, it would show that Systems and Finders older than the version that originally shipped with the HD20 could in fact be used to boot the HD20.

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I did confirm that your virgin System 2.1 / Finder 5.0 disk would not boot my HD20 if my HD20 had System 4.1 and Finder 6.0 on it.

 

Thats what I was looking for, a litmus test! So what that means is the original HD20 startup disk will not work with older systems. I'll bet System 3.0 & Finder 5.1 (or maybe even 5.0) will work just fine with a newer system. I read an interesting article in MacTech that detailed the changes thoroughly and SYstem 3.0 and up really changed the System resources considerably.

 

Otherwise, I think we are starting to repeat ourselves! LOL At this point I am interested in the pure mechanics of how the HD20 INIT works and not so much the practicality of it. I think we have the MFS formatting dilemma behind us.

 

As for MFS partitioning, of course it works. I have an application called MacServe which was the original AppleTalk disk serving and network printer software dating back to the Lisa. Essentially that allowed you to partition an HD 20 with HFS & MFS volumes. And originally they were MFS only. I saw it explained somewhere that HFS folders are basically just disk partitions. Since my HD20 is currently not working, I have set this up on a ZIP 100 drive running System 3.2/F5.3 that boots the Mac. The key is, the drive must be formatted according to the manufacturer instructions. So the HD20 (like the ZIP) must be initialized HFS, then MacServe partitions the drive however you want.

 

I'm basically curious if the HD20 could be initialized completely MFS and therefore used with an MFS only system. I agree partitioning it would be the only practical way to use it.

 

However, testing System 2.1 and Finder 4.1 on my HD20, and then trying the S2.1F4.1 boot floppy with a virgin HD20 INIT may be an interesting test. If it works, it would show that Systems and Finders older than the version that originally shipped with the HD20 could in fact be used to boot the HD20.

 

I would certainly be interested in the results. And if using my ZIP 100 drive is any indication, entirely possible. As long as the Mac can see and understand the drive and there is a system on the drive that the Mac understands, then it shouldn't matter what version it is. However, as you pointed out Finder 4.1 is NOT HFS aware. I believe that the normal version of the HD20 INIT makes System 2.1 HFS aware, but does nothing for the Finder which is why the System can see HFS formatted disks, but cant write to them, or discern their contents & folders. That seems to be the Finder's job, to find the folder "partitions" or file structures. However, you wouldn't want to use such a system if it did work since you would royally screw up your data by writing files MFS onto an HFS formated disk. The only variable is whether something in the "hand-off" would prevent it from loading.

 

There is a lot of info on these pages of invaluable nature for working with and further investigating an 800K drive, HD20 and MFS/HFS Systems. However, the main goal of working with 800K MFS disks has been achieved by not one, but two and conceivably other methods. Clearly the HD20 is best formatted for practical use as an HFS drive and partitioned accordingly using existing software and other solutions. I will keep working on the MFS issue for the large volume access on a 128K as that is where my goal lies and report back, but until someone is ready to initialize an HD20 most of it will be theoretical.

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